Design of a ZnS/CdS/rGO composite nanosheet photocatalyst with multi-interface electron transfer for high conversion of CO2

Constructing a multi-interface electron transfer path is one of the ideal methods to improve the migration rate of photogenerated electrons in semiconductors. In this work, a ZnS/CdS NSs heterojunction was engineered on the surface of reduced graphene oxide (rGO) by calcination and hydrothermal methods, combining the electron transfer ability of the heterojunction with the electron capture ability of graphene. In ZnS/CdS/rGO, the photogenerated electrons transfer from ZnS → CdS, CdS → rGO and ZnS → CdS → rGO, establishing the multi-interface transfer path and improving the migration efficiency of photogenerated electrons. Furthermore, the existence of rGO greatly improves the CO2 molecule adsorption ability and the material stability of the photocatalyst. As expected, the as-prepared ZnS/CdS/rGO photocatalyst shows excellent performance in photoreduction of CO2 and the yield of CO was 38.77 μmol g−1 after 4 h UV-vis light irradiation, which is 21.7 times that of pure ZnS NSs (1.78 μmol g−1). The ZnS/CdS/rGO photocatalyst also displays favorable stability after multiple photocatalytic cycles. Lastly, the possible reaction mechanism is discussed in detail.